Also, it's not like being fully optimized in 63's will automaticly make you invincible. You still have to know how to play your character well and the boss mechanics

^^^ This. 100 times this.

A guy who bought a full DG set and then walked straight into 16 Man NiM EC would have a very very very small chance of getting the Warstalker title. Or downing 16 man NiM EC Kephess. Or 8 man NiM EC Kephess for that matter.